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  • 1101.
    Ahmad, M. Rauf
    et al.
    Uppsala University, Sweden; Swedish University of Agriculture Science, Sweden; University of Munich, Germany.
    von Rosen, Dietrich
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, Faculty of Science & Engineering. Swedish University of Agriculture Science, Sweden.
    Tests for high-dimensional covariance matrices using the theory of U-statistics2015In: Journal of Statistical Computation and Simulation, ISSN 0094-9655, E-ISSN 1563-5163, Vol. 85, no 13, p. 2619-2631Article in journal (Refereed)
    Abstract [en]

    Test statistics for sphericity and identity of the covariance matrix are presented, when the data are multivariate normal and the dimension, p, can exceed the sample size, n. Under certain mild conditions mainly on the traces of the unknown covariance matrix, and using the asymptotic theory of U-statistics, the test statistics are shown to follow an approximate normal distribution for large p, also when p and#8811;n. The accuracy of the statistics is shown through simulation results, particularly emphasizing the case when p can be much larger than n. A real data set is used to illustrate the application of the proposed test statistics.

  • 1102.
    Ahmad, M. Rauf
    et al.
    Uppsala University, Sweden; Swedish University of Agriculture Science, Sweden.
    von Rosen, Dietrich
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology. Swedish University of Agriculture Science, Sweden.
    Tests of Covariance Matrices for High Dimensional Multivariate Data Under Non Normality2015In: Communications in Statistics - Theory and Methods, ISSN 0361-0926, E-ISSN 1532-415X, Vol. 44, no 7, p. 1387-1398Article in journal (Refereed)
    Abstract [en]

    Ahmad et al. (in press) presented test statistics for sphericity and identity of the covariance matrix of a multivariate normal distribution when the dimension, p, exceeds the sample size, n. In this note, we show that their statistics are robust to normality assumption, when normality is replaced with certain mild assumptions on the traces of the covariance matrix. Under such assumptions, the test statistics are shown to follow the same asymptotic normal distribution as under normality for large p, also whenp greater thangreater than n. The asymptotic normality is proved using the theory of U-statistics, and is based on very general conditions, particularly avoiding any relationship between n and p.

  • 1103.
    Ahmad, M. Rauf
    et al.
    Swedish University of Agricultural Sciences, Uppsala, Sweden and Department of Statistics, Uppsala University, Sweden.
    von Rosen, Dietrich
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    Singull, Martin
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, The Institute of Technology.
    A note on mean testing for high dimensional multivariate data under non-normality2013In: Statistica neerlandica (Print), ISSN 0039-0402, E-ISSN 1467-9574, Vol. 67, no 1, p. 81-99Article in journal (Refereed)
    Abstract [en]

    A test statistic is considered for testing a hypothesis for the mean vector for multivariate data, when the dimension of the vector, p, may exceed the number of vectors, n, and the underlying distribution need not necessarily be normal. With n,p→∞, and under mild assumptions, but without assuming any relationship between n and p, the statistic is shown to asymptotically follow a chi-square distribution. A by product of the paper is the approximate distribution of a quadratic form, based on the reformulation of the well-known Box's approximation, under high-dimensional set up. Using a classical limit theorem, the approximation is further extended to an asymptotic normal limit under the same high dimensional set up. The simulation results, generated under different parameter settings, are used to show the accuracy of the approximation for moderate n and large p.

  • 1104.
    Ahmad, Maqsood
    et al.
    Base Engine & Materials Technology, Volvo Group, Gothenburg.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    König, Mathias
    Materials Technology for Basic Engine, Scania CV, Södertälje.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Bending Fatigue Behavior of Blast Cleaned Grey Cast Iron2017In: Residual Stresses 2016: ICRS-10, Materials Research Proceedings 2 (2016), 2017, Vol. 2, p. 193-198Conference paper (Refereed)
    Abstract [en]

    This paper presents a detailed study on the effect of an industrial blast cleaning process on the fatigue behavior of a grey cast iron with regard to the residual stresses and microstructural changes induced by the process. A comparison was also made to the effect of a machining operation which removed the casting skin layer. The blast cleaning process was found to greatly improve the fatigue resistance in both the low and high cycle regimes with a 75% increase in the fatigue limit. Xray diffraction measurements and scanning electron microscopic analyses showed that the improvement was mainly attributed to compressive residual stresses in a surface layer up to 800 μm in thickness in the blast cleaned specimens. The machining also gave better fatigue performance with a 30% increase in the fatigue limit, which was ascribed to the removal of the weaker casting skin layer.

  • 1105.
    Ahmad, Mohammed Metwally Gomaa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. National Research Centre, Egypt.
    Yazdi, Gholamreza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boshta, M.
    National Research Centre, Egypt.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Farag, B. S.
    National Research Centre, Egypt.
    Osman, M. B. S.
    Ain Shams University, Egypt.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Effect of precursor solutions on the structural and optical properties of sprayed NiO thin films2017In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 64, p. 32-38Article in journal (Refereed)
    Abstract [en]

    Nickel oxide thin films were deposited by a simple and low-cost spray pyrolysis technique using three different precursors: nickel nitrate, nickel chloride, and nickel acetate on corning glass substrates. X-ray diffraction show that the NiO films are polycrystalline and have a cubic crystal structure, although predominantly with a preferred 111-orientation in the growth direction and a random in-plane orientation. The deconvolution of the Ni 2p and O 1s core level X-ray photoelectron-spectra of nickel oxides produced by using different precursors indicates a shift of the binding energies. The sprayed NiO deposited from nickel nitrate has an optical transmittance in the range of 60-65% in the visible region. The optical band gap energies of the sprayed NiO films deposited from nickel nitrate, nickel chloride and nickel acetate are 3.5, 3.2 and 3.43 eV respectively. Also, the extinction coefficient and refractive index of NiO films have been calculated from transmittance and reflectance measurements. The average value of refractive index for sprayed films by nickel nitrate, nickel chloride and nickel acetate are 2.1, 1.6 and 1.85 respectively. It is revealed that the band gap and refractive index of NiO films by using nickel nitrate corresponds to the commonly reported values. We attribute the observed behavior in the optical band gap and optical constants as due to the change of the Ni/O ratio.

  • 1106.
    Ahmad, Shakeel
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Stimuli Generation Techniques for On-Chip Mixed-Signal Test2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    With increased complexity of the contemporary very large integrated circuits the need for onchip test addressing not only the digital but also analog and mixed-signal RF blocks has emerged. The standard production test has become more costly and the instrumentation is pushed to its limits by the leading edge integrated circuit technologies. Also the chip performance for high frequency operation and the area overhead appear a hindrance in terms of the test access points needed for the instrumentation-based test. To overcome these problems, test implemented on a chip can be used by sharing the available resources such as digital signal processing (DSP) and A/D, D/A converters to constitute a built-in-self-test. In this case, the DSP can serve both as a stimuli generator and response analyzer.

    Arbitrary test signals can be achieved using DSP. Specifically, the ΣΔ modulation technique implemented in software is useful to encode a single- or two-tone stimulus as a onebit sequence to generate a spectrally pure signal with a high dynamic range. The sequence can be stored in a cyclic memory on a chip and applied to the circuit under test using a buffer and a simple reconstruction filter. In this way ADC dynamic test for harmonic and intermodulation distortion is carried out in a simple setup. The FFT artifacts are avoided by careful frequency planning for low-pass and band-pass ΣΔ encoding technique. A noise shaping based on a combination of low- and band-pass ΣΔ modulation is also useful providing a high dynamic range for measurements at high frequencies that is a new approach. However, a possible asymmetry between rise and fall time due to CMOS process variations in the driving buffer results in nonlinear distortion and increased noise at low frequencies. A simple iterative predistortion technique is used to reduce the low frequency distortion components by making use of an on-chip DC calibrated ADC that is another contribution of the author.

    Some tests, however, like the two-tone RF test that targets linearity performance of a radio receiver, require test stimuli based on a dedicated hardware. For the measurement of the thirdor second-intercept point (IP3/IP2) a spectrally clean stimulus is essential. Specifically, the second- or third-order harmonic or intermodulation products of the stimulus generator should be avoided as they can obscure the test measurement. A challenge in this design is the phase noise performance and spurious tones of the oscillators, and also the distortion-free addition of the two tones. The mutual pulling effect can be minimized by layout isolation techniques.

    A new two-tone RF generator based on a specialized phase-locked loop (PLL) architecture is presented as a viable solution for IP3/IP2 on-chip test. The PLL provides control over the frequency spacing of two voltage controlled oscillators. For the two-tone stimulus a highly linear analog  adder is designed to limit distortion which could obscure the IP3 test. A specialized feedback circuit in the PLL is proposed to overcome interference by the reference spurs. The circuit is designed using 65 nm CMOS process. By using a fine spectral resolution the observed noise floor can be reduced to enable the measurement of second- or third-order intermodulation product tones. This also reflects a tradeoff between the test time and the test performance. While the test time to collect the required number of samples can be of milliseconds the number of samples need not be excessive, since the measurements are carried out at the receiver baseband, where the required sampling frequency is relatively low.

    List of papers
    1. ADC on-Chip Dynamic Test by PWM Technique
    Open this publication in new window or tab >>ADC on-Chip Dynamic Test by PWM Technique
    2008 (English)In: International Conference on Signals and Electronic Systems, IEEE , 2008, p. 15-18Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper investigates the feasibility of pulse width modulation technique (PWM) for dynamic test of ADCs used for high speed applications. The requirements and limitations of digital PWM signal to noise ratio (SNR) are discussed in terms of pulse-width resolution corresponding to the choice of the carrier- and clock frequency of a pulse-width generator. The PWM SNR response is measured by FFT using coherent sampling for different PWM resolution. Low-pas filtering removing high frequency PWM components is introduced as well to improve PWM SNR and prevent intermodulation effects, which tend to hamper the harmonic distortion test (HD). As an example a 4-bit first-order SigmaDelta ADC under dynamic test is simulated and the requirements for PWM resolution with respect to SNR and HD measurements are identified.

    Place, publisher, year, edition, pages
    IEEE, 2008
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-43029 (URN)10.1109/ICSES.2008.4673345 (DOI)70959 (Local ID)78-83-88309-47-2 (ISBN)70959 (Archive number)70959 (OAI)
    Conference
    International Conference on Signals and Electronic Systems, ICSES '08, 14-17 Sept, Krakow, Poland
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2010-11-17Bibliographically approved
    2. On-chip Stimuli Generation for ADC Dynamic Test by ΣΔ Technique
    Open this publication in new window or tab >>On-chip Stimuli Generation for ADC Dynamic Test by ΣΔ Technique
    2009 (English)In: Proceedings in European Conference on Circuit Theory and Design 2009 (ECCTD´09), Antalya, Turkey, IEEE , 2009, p. 105-108Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper presents application of the ΣΔ modulation technique to the on-chip dynamic test for A/D converters. The wanted stimulus such as a single- or two-tone signal is encoded into one-bit ΣΔ sequence, which after simple low-pass filtering is applied to the circuit under test with low noise and without distortion. In this way a large dynamic range is achieved making the performance harmonic- and intermodulation dynamic test viable. By a systematic approach we select the order and type of a ΣΔ modulator, and develop the frequency plan suitable for spectral measurements on a chip. The technique is illustrated by simulation of a practical ADC under test.

    Place, publisher, year, edition, pages
    IEEE, 2009
    Keywords
    Stimuli generation, on-chip test
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-20668 (URN)10.1109/ECCTD.2009.5274977 (DOI)000276473700027 ()978-1-4244-3896-9 (ISBN)
    Conference
    European Conference on Circuit Theory and Design, ECCTD 2009, 23-27 Aug., Antalya
    Note
    ©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEEAvailable from: 2009-10-13 Created: 2009-09-16 Last updated: 2010-11-17Bibliographically approved
    3. Two-tone PLL for on-chip IP3 test
    Open this publication in new window or tab >>Two-tone PLL for on-chip IP3 test
    2010 (English)In: Proceedings of IEEEInternational Symposium on Circuits and Systems, (ISCAS 10), IEEE , 2010, p. 3549-3552Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper addresses a built-in-self-test (BiST) to characterize IP3 linearity of a RF receiver front-end. A two-tone stimulus is generated by a phase-lock loop (PLL) in GHz frequency range. The PLL is designed to keep the frequency difference between the two tones under control and in this way to avoid a possible injection-locking. One of the oscillation frequencies and the difference (beat) frequency can be externally controlled. According to the test requirements the phase noise and nonlinear distortion of the two-tone generator are considered as a merit for the VCO and analog adder design. A highly linear analog adder with output referred IP3 of more than +15 dBm is used to generate the RF stimulus. The two-tone power across 50 Ω receiver input impedance can be more than -25 dBm with very low intermodulation distortion of PIM3 = -75 dBc. The receiver performance is not affected significantly by the test set-up. Simulations for linearity and noise performance of the PLL designed in 65nm CMOS show sufficient potential for on-chip IP3 measurements in the GHz frequency range.

    Place, publisher, year, edition, pages
    IEEE, 2010
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-61666 (URN)10.1109/ISCAS.2010.5537812 (DOI)978-1-4244-5308-5 (ISBN)
    Conference
    Proceedings of 2010 IEEE International Symposium on Circuits and Systems (ISCAS), May 30-June, Paris, France
    Available from: 2010-11-17 Created: 2010-11-17 Last updated: 2010-11-17
    4. Cancellation of Spurious Spectral Components in One-Bit Stimuli Generator
    Open this publication in new window or tab >>Cancellation of Spurious Spectral Components in One-Bit Stimuli Generator
    2010 (English)In: Proceedings of IEEEInternational Conference on Signals and Electronic Systems, (ICSES 10) / [ed] Andrzej Pułka and Tomasz Golonek, IEEE , 2010, p. 393-396Conference paper, Published paper (Refereed)
    Abstract [en]

    This work presents a cancellation technique of non-linear distortion components of one-bit digital stimulus sequence which is generated in software by a ΣΔ modulator. The stimulus is stored in a cyclic memory and applied to a circuit under test through a driving buffer and a simple lowpass reconstruction filter. The distortion components originate from buffer imperfections which result in a possible asymmetry between rising and falling edges of a NRTZ waveform representing the encoded stimulus. We show that the distortion components can be cancelled by using a simple predistortion technique. In addition an on-chip DC-calibrated ADC can be used to identify the second-order nonlinear products of the driving buffer. This procedure allows for cancellation of all the second-order distortions before the actual test and it can be extended to the third order terms as well.

    Place, publisher, year, edition, pages
    IEEE, 2010
    National Category
    Signal Processing
    Identifiers
    urn:nbn:se:liu:diva-61668 (URN)978-1-4244-5307-8 (ISBN)
    Conference
    International Conference on Signals and Electronic Systems (ICSES), 7-10 Sept, Gliwice, Poland
    Available from: 2010-11-17 Created: 2010-11-17 Last updated: 2015-09-14Bibliographically approved
    5. Design of Two-Tone RFGenerator for On-Chip IP3/IP2 Test
    Open this publication in new window or tab >>Design of Two-Tone RFGenerator for On-Chip IP3/IP2 Test
    (English)Manuscript (preprint) (Other academic)
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-61669 (URN)
    Conference
    IEEE Transactions on Circuits and Systems–II
    Available from: 2010-11-17 Created: 2010-11-17 Last updated: 2010-11-17
    6. One-bit ΣΔ Encoded StimulusGeneration for on-Chip ADC Test
    Open this publication in new window or tab >>One-bit ΣΔ Encoded StimulusGeneration for on-Chip ADC Test
    2010 (English)In: Journal of electronic testing, ISSN 0923-8174, E-ISSN 1573-0727Article in journal (Other academic) Submitted
    Place, publisher, year, edition, pages
    Springer, 2010
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-61687 (URN)
    Available from: 2010-11-17 Created: 2010-11-17 Last updated: 2017-12-12Bibliographically approved
  • 1107.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Azizi, Kaveh
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Esmaeil Zadeh, Iman
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Two-tone PLL for on-chip IP3 test2010In: Proceedings of IEEEInternational Symposium on Circuits and Systems, (ISCAS 10), IEEE , 2010, p. 3549-3552Conference paper (Refereed)
    Abstract [en]

    This paper addresses a built-in-self-test (BiST) to characterize IP3 linearity of a RF receiver front-end. A two-tone stimulus is generated by a phase-lock loop (PLL) in GHz frequency range. The PLL is designed to keep the frequency difference between the two tones under control and in this way to avoid a possible injection-locking. One of the oscillation frequencies and the difference (beat) frequency can be externally controlled. According to the test requirements the phase noise and nonlinear distortion of the two-tone generator are considered as a merit for the VCO and analog adder design. A highly linear analog adder with output referred IP3 of more than +15 dBm is used to generate the RF stimulus. The two-tone power across 50 Ω receiver input impedance can be more than -25 dBm with very low intermodulation distortion of PIM3 = -75 dBc. The receiver performance is not affected significantly by the test set-up. Simulations for linearity and noise performance of the PLL designed in 65nm CMOS show sufficient potential for on-chip IP3 measurements in the GHz frequency range.

  • 1108.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Azizi, Kaveh
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Esmaeil Zadeh, Iman
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Two-Tone PLL for on-Chip IP3 Test2010In: Swedish System-on-Chip Conference, 2010Conference paper (Other academic)
  • 1109.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    ADC on-Chip Dynamic Test by PWM Technique2008In: International Conference on Signals and Electronic Systems, IEEE , 2008, p. 15-18Conference paper (Refereed)
    Abstract [en]

    This paper investigates the feasibility of pulse width modulation technique (PWM) for dynamic test of ADCs used for high speed applications. The requirements and limitations of digital PWM signal to noise ratio (SNR) are discussed in terms of pulse-width resolution corresponding to the choice of the carrier- and clock frequency of a pulse-width generator. The PWM SNR response is measured by FFT using coherent sampling for different PWM resolution. Low-pas filtering removing high frequency PWM components is introduced as well to improve PWM SNR and prevent intermodulation effects, which tend to hamper the harmonic distortion test (HD). As an example a 4-bit first-order SigmaDelta ADC under dynamic test is simulated and the requirements for PWM resolution with respect to SNR and HD measurements are identified.

  • 1110.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Cancellation of Spurious Spectral Components in One-Bit Stimuli Generator2010In: Proceedings of IEEEInternational Conference on Signals and Electronic Systems, (ICSES 10) / [ed] Andrzej Pułka and Tomasz Golonek, IEEE , 2010, p. 393-396Conference paper (Refereed)
    Abstract [en]

    This work presents a cancellation technique of non-linear distortion components of one-bit digital stimulus sequence which is generated in software by a ΣΔ modulator. The stimulus is stored in a cyclic memory and applied to a circuit under test through a driving buffer and a simple lowpass reconstruction filter. The distortion components originate from buffer imperfections which result in a possible asymmetry between rising and falling edges of a NRTZ waveform representing the encoded stimulus. We show that the distortion components can be cancelled by using a simple predistortion technique. In addition an on-chip DC-calibrated ADC can be used to identify the second-order nonlinear products of the driving buffer. This procedure allows for cancellation of all the second-order distortions before the actual test and it can be extended to the third order terms as well.

  • 1111.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering. Univ Management and Technol, Pakistan.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Design of Two-Tone RF Generator for On-Chip IP3/IP2 Test2019In: Journal of electronic testing, ISSN 0923-8174, E-ISSN 1573-0727, Vol. 35, no 1, p. 77-85Article in journal (Refereed)
    Abstract [en]

    In this paper a built-in-self-test (BiST) aimed at the third and second intercept point (IP3/IP2) characterization of RF receiver is discussed with a focus on a stimulus generator. The generator is designed based on a specialized phase-lock loop (PLL) architecture with two voltage controlled oscillators (VCOs) operating in GHz frequency range. The objective of PLL is to keep the VCOs frequency spacing under control. According to the test requirements the phase noise and nonlinear distortion of the two-tone generator are considered as a merit for the design of VCOs and analog adder. The PLL reference spurs, critical for the IP3 measurement, are avoided by means of a frequency doubling technique. The circuit is designed in 65nm CMOS. A highly linear analog adder with OIP3amp;gt;+15dBm and ring VCOs with phase noise amp;lt; -104 dBc/Hz at 1MHz offset are used to generate the RF stimulus of total power greater than -22dBm. In simulations a performance sufficient for IP3/IP2 test of a typical RF CMOS receiver is demonstrated.

  • 1112.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Design of Two-Tone RFGenerator for On-Chip IP3/IP2 TestManuscript (preprint) (Other academic)
  • 1113.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    On-Chip Spectral Test for High-Speed ADCs by ΣΔ Technique2011In: European Conference on Circuit Theory and Design (ECCTD), Linköping, Sweden: IEEE conference proceedings, 2011, p. 661-664Conference paper (Refereed)
    Abstract [en]

    Application of the ΣΔ modulation technique to the on-chip spectral test for high-speed A/D converters is presented. The harmonic HD2/HD3 and intermodulation IM2/IM3 test is obtained with one-bit ΣΔ sequence stored in a cyclic memory or generated on line, and applied to an ADC under test through a driving buffer and a simple reconstruction filter. To achieve a dynamic range (DR) suitable for high-performance spectral measurements a frequency plan is used taking into account the type of ΣΔ modulation (low-pass and band-pass) including the FFT processing gain. Higher order modulation schemes are avoided to manage the ΣΔ quantization noise without resorting to a more complicated filter. For spectral measurements up to the Nyquist frequency, we propose a dedicated low-pass/band-pass ΣΔ modulation scheme that limits spreading of the low-frequency quantization noise by ADC under test that tends to obstruct the test measurements at high frequencies. Correction technique for NRTZ encoding suitable for ADCs with very high clock frequencies is put in perspective. The presented technique is illustrated by simulation examples of a Nyquist-rate ADC under test.

  • 1114.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    On-chip Stimuli Generation for ADC Dynamic Test by ΣΔ Technique2009In: Proceedings in European Conference on Circuit Theory and Design 2009 (ECCTD´09), Antalya, Turkey, IEEE , 2009, p. 105-108Conference paper (Refereed)
    Abstract [en]

    This paper presents application of the ΣΔ modulation technique to the on-chip dynamic test for A/D converters. The wanted stimulus such as a single- or two-tone signal is encoded into one-bit ΣΔ sequence, which after simple low-pass filtering is applied to the circuit under test with low noise and without distortion. In this way a large dynamic range is achieved making the performance harmonic- and intermodulation dynamic test viable. By a systematic approach we select the order and type of a ΣΔ modulator, and develop the frequency plan suitable for spectral measurements on a chip. The technique is illustrated by simulation of a practical ADC under test.

  • 1115.
    Ahmad, Shakeel
    et al.
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Dabrowski, Jerzy
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    One-bit ΣΔ Encoded StimulusGeneration for on-Chip ADC Test2010In: Journal of electronic testing, ISSN 0923-8174, E-ISSN 1573-0727Article in journal (Other academic)
  • 1116.
    Ahmad, Sura
    et al.
    Linköping University, Department of Management and Engineering.
    Elmér, Birgitta
    Linköping University, Department of Management and Engineering.
    Massa, massa, massa ansvar: En intervjustudie kring förberedelsen inför vuxenblivandet,baserad på sex ungdomars röster2008Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

     

    Denna uppsats bygger på en kvalitativ studie av sex gymnasieelevers tankar kring förberedelsen inför vuxenblivandet samt skolans och familjens vägledande betydelse i denna process. Ungdomarnas verklighet stödjer de senmoderna teorierna om att dagens ungdomar försenas i sitt vuxenblivande i och med att studietiden har förlängts och därmed försenas även inträdet i arbetslivet. Ur samtalen med dessa ungdomar får vi inte bilden av att familjen och därav traditionen spelat ut sin roll, så som de senmoderna teoretikerna menar. Tvärtom framkommer det tydligt att familjen fortfarande innehar den centrala vägledande rollen i dessa ungdomars liv och leverne. Skolans roll i respondenternas förberedelse inför steget efter gymnasiet är inte samstämmig, då individualismen präglar några av informanterna, som ger uttryck för en mer långtgående individualiserad syn på sitt vuxenblivande. Detta resulterar i att dessa ungdomar starkt betonar sitt eget individuella ansvar framför skolans vägledande betydelse. Resultatet av denna studie visar att dessa ungdomar har bristande kunskaper vad gäller den praktiska delen i samhällssystemet samt att deras kunskapsnivå skiljer sig åt beroende på vilka kurser av ämnet samhällskunskap de har läst. Det är tydligt att de som har läst samhällskunskap C besitter mer kunskaper kring det praktiska i samhället. Som blivande samhällskunskapslärare anser vi att eleverna har rätt till denna kunskap oavsett gymnasieprogram, därav borde en obligatorisk kurs som belyser det praktiska aspekterna av samhällssystemet införas under det sista året på gymnasiet.

     

  • 1117.
    Ahmad, Tariq
    et al.
    Yale Univ, CT USA; Yale Univ, CT USA.
    Lund, Lars H.
    Karolinska Inst, Sweden; Karolinska Univ Hosp, Sweden.
    Rao, Pooja
    Qure Ai, India.
    Ghosh, Rohit
    Qure Ai, India.
    Warier, Prashant
    Qure Ai, India.
    Vaccaro, Benjamin
    Yale Univ, CT USA; Yale Univ, CT USA.
    Dahlström, Ulf
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Cardiology in Linköping.
    OConnor, Christopher M.
    Duke Univ, NC USA.
    Felker, G. Michael
    Duke Univ, NC USA.
    Desai, Nihar R.
    Yale Univ, CT USA; Yale Univ, CT USA.
    Machine Learning Methods Improve Prognostication, Identify Clinically Distinct Phenotypes, and Detect Heterogeneity in Response to Therapy in a Large Cohort of Heart Failure Patients2018In: Journal of the American Heart Association: Cardiovascular and Cerebrovascular Disease, ISSN 2047-9980, E-ISSN 2047-9980, Vol. 7, no 8, article id e008081Article in journal (Refereed)
    Abstract [en]

    Background-Whereas heart failure (HF) is a complex clinical syndrome, conventional approaches to its management have treated it as a singular disease, leading to inadequate patient care and inefficient clinical trials. We hypothesized that applying advanced analytics to a large cohort of HF patients would improve prognostication of outcomes, identify distinct patient phenotypes, and detect heterogeneity in treatment response. Methods and Results-The Swedish Heart Failure Registry is a nationwide registry collecting detailed demographic, clinical, laboratory, and medication data and linked to databases with outcome information. We applied random forest modeling to identify predictors of 1-year survival. Cluster analysis was performed and validated using serial bootstrapping. Association between clusters and survival was assessed with Cox proportional hazards modeling and interaction testing was performed to assess for heterogeneity in response to HF pharmacotherapy across propensity-matched clusters. Our study included 44 886 HF patients enrolled in the Swedish Heart Failure Registry between 2000 and 2012. Random forest modeling demonstrated excellent calibration and discrimination for survival (C-statistic=0.83) whereas left ventricular ejection fraction did not (C-statistic=0.52): there were no meaningful differences per strata of left ventricular ejection fraction (1-year survival: 80%, 81%, 83%, and 84%). Cluster analysis using the 8 highest predictive variables identified 4 clinically relevant subgroups of HF with marked differences in 1-year survival. There were significant interactions between propensity-matched clusters (across age, sex, and left ventricular ejection fraction and the following medications: diuretics, angiotensin-converting enzyme inhibitors, )i-blockers, and nitrates, Pamp;lt;0.001, all). Conclusions-Machine learning algorithms accurately predicted outcomes in a large data set of HF patients. Cluster analysis identified 4 distinct phenotypes that differed significantly in outcomes and in response to therapeutics. Use of these novel analytic approaches has the potential to enhance effectiveness of current therapies and transform future HF clinical trials.

  • 1118. Ahmad, Tausif
    et al.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Hybrid Color Halftoning2010Conference paper (Refereed)
  • 1119.
    Ahmadi, Ahmad
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Genetic predisposition and risk factors for neurodegenerative diseases2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The inter-individual variability in biotransformation, may lead to differences in activation and detoxification of both endogenous and exogenous compounds. Polymorphism studies in such genes were applied for Parkinson's disease (PD) and Chronic toxic encephalopathy (CTE), two diseases influenced by both genetic and enviromnental factors.

    An elevated median age for the onset of PD was found among GS1M1 gene carriers compared to PD patients being GS1M1 null genotypes (68 years versus 57 years). No similar difference was found for GSTT1. mEPHX (113HH) isoform, which has been suggested as a low activity variant, is over represented in PD patients (OR=3.8, CI 95%, 1.2-11.8).

    Monoamine oxidases (MAO-A and -B) are important in the dopamine metabolism and in the detoxification of neurotoxins and genetic variants in these genes have earlier been assigned to PD. However, no difference was revealed between any of the polymorphisms studied in the MAO-A and -B genes and PD. Smoking displayed an enviromnental exposure with a strong decreased risk for PD in this study (OR=0.40 for men and OR=0.48 for women) but no obvious interaction with the MAO genotypes could be observed.

    Mitochondrial dysfunction and oxidative stress have been hypothesized to contribute to the pathogenesis of PD. The superoxide dismutases (SOD) potentially play an important role in PD by detoxifying superoxide radicals in mitochondria. Polymorphisms neither in superoxide dismutase 2 (SOD2) nor mitochondrial complex I subunit, NDUFV2, were associated with PD.

    An increased risk ratio for CTE was found in smokers with the GSTM1 null genotype (RR=2.5, Cl 95%, 1.4-4.2) or the GSTT1 null genotype (RR=1.4, Ci 95%, 1.02-2.0). In non-smokers GS1M1 null genotype did not confer any risk for CTE. Polymorphisms in mEPHX were not associated with an increased risk for CTE.

    Thus, various genetic and enviromnental factors most likely influence both PD and solvent-induced CTE. Detoxification pathways may represent important protective mechanisms against reactive intermediates, thus genetic predisposition in these pathways could modify the susceptibility and onset of PD and solvent-induced CTE.

    List of papers
    1. GSTM1 and mEPHX polymorphisms in Parkinson's disease and age of onset
    Open this publication in new window or tab >>GSTM1 and mEPHX polymorphisms in Parkinson's disease and age of onset
    Show others...
    2000 (English)In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 269, no 3, p. 676-680Article in journal (Refereed) Published
    Abstract [en]

    Both environmental and genetic factors are involved in the development of PD and biotransformation of exogenous and endogenous compounds and may play a role in inter-individual susceptibility. Therefore, we investigated the presence of null genotypes of GSTM1, GSTT1, and two polymorphisms of mEPHX in subjects with Parkinson's disease and in a reference population. The study included 35 male PD patients and a male control group including 283 subjects. Homozygosity of the histidine (H) 113 isoform of mEPHX was significantly increased in PD patients (odds ratio = 3.8 CI 95% 1.2–11.8) and analysis of allele frequencies displayed an increased frequency of the H-allele among PD patients (odds ratio = 1.9 CI 95% 1.1–3.3). However, a significantly elevated median age for the onset of PD was found among GSTM1 gene carriers (median age = 68 years) compared to PD patients being GSTM1 null genotypes (median age = 57 years). Our observations suggest that (H) 113 isoform of mEPHX, which has been suggested as a low activity isoform, is overrepresented in PD patients and that inherited carriers of the GSTM1 gene postpone the onset of PD. These detoxification pathways may represent important protective mechanisms against reactive intermediates modifying the susceptibility and onset of PD.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-24837 (URN)10.1006/bbrc.2000.2338 (DOI)9235 (Local ID)9235 (Archive number)9235 (OAI)
    Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
    2. Monoamine oxidase A and B genes polymorphisms in Parkinson's disease
    Open this publication in new window or tab >>Monoamine oxidase A and B genes polymorphisms in Parkinson's disease
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Parkinson's disease (PD) is a common progressive neurodegenerative disorder characterized by degeneration of nig:rostriatal dopaminergic neurons including the loss of cell bodies in the pars compacta of substantia nigra (SN). The mechanism for neurodegeneration is unknown, but the pathogenesis is considered to be multifactorial involving exposure for toxins, genetic inheritance, age, oxidative stress and mitochondrial electron transport chain defects. This study has been focused on polymorphisms in the genes for the enzymes monoamine oxidase A and B (MAO-A, MAO-B) and relation to smoking for the development of idiopathic Parkinson's disease. MAO enzymes are important in the dopamine metabolism and in the detoxification of neurotoxins. During metabolism of dopamine, MAO generates large amounts of free radicals and hydrogen peroxide, and may damage the neurons in substantia nigra, which has been suggested as a pathologic mechanism for PD.

    Blood samples were collected from 256 PD patients, age 30-80 years, and 582 unrelated control individuals, age 31 - 78 years, from southeastern Sweden.

    Two polymorphisms (exon 8 and exon 14) located in the MAO-A gene and one polymorphism located in the MA O-B gene were examined, with denatming HPLC, PCR-RFLP or DNA sequencing. Genotype and allele frequencies were determined for patients and controls. No statistical significant difference was revealed between any of the polymorphisms in the MAO-A and MAO-B genes and Parkinson's disease. Smoking displayed an enviromnental exposure with a strong decreased risk for both male (OR=0.40, 95% CI 0.25 - 0.63) and female (OR=0.48, 95% CI 0.25-0.89) PD without any interaction with MAO genotype.

    The polymorphisms in MAO genes might therefore not be acting as modifiers of risk for developing of PD either by itself or by interacting with smoking. With respect to the size of the study (256 PD patients and 582 controls) MAO polymorphisms do not represent any predisposing factor or a weak PD susceptibility factor.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84799 (URN)
    Available from: 2012-10-22 Created: 2012-10-22 Last updated: 2012-10-22Bibliographically approved
    3. Manganese superoxide dismutase and NDUFV2 polymorphisms and susceptibility to Parkinson's disease
    Open this publication in new window or tab >>Manganese superoxide dismutase and NDUFV2 polymorphisms and susceptibility to Parkinson's disease
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Mitochondrial dysfunction has been hypothesized to contribute to the pathogenesis of Parkinson's disease (PD). Oxidative stress and production of oxygen radicals is produced in mitochondria. The superoxide dismutases (SOD) potentially play an important role in PD by detoxifying superoxide radicals. Oxidative stress has also an important role to decrease Complex I activity in the mitochondria. In addition, Complex I contains several subunits, where one, NDUFV2, plays a major role in the electron transport pathway of Complex I in substantia nigra.

    The aim of this project was to study polymorphisms in MTS-SOD2 and the Complex I subunit, NDUFV2 as predisposing factors for the development of idiopathic PD.

    Blood samples from 200 PD and 404 population controls were collected from the Southeastern part of Sweden. DNA was isolated and the polymorphisms were analyzed by pyrosequencing and direct dideoxy termination sequencing.

    Genotypes and allele frequencies were compared for the patient and control groups with Χ2 statistics. No statistical significant difference was evident for any of the polymorphisms neither in MTS-SOD2 (OR=0<85, 95% CI, 0<52-1.38) nor NDUFV2 (OR=0.64, 95% CI, 0.24-1.64) genes and PD.

    These results indicate that the MTS-SOD2 and NDUFV2 gene variants do not contribute to PD pathogenesis.

    Keywords
    SOD2, NDUFV2, polymorphisms, Parkinson's disease
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84800 (URN)
    Available from: 2012-10-22 Created: 2012-10-22 Last updated: 2012-10-22Bibliographically approved
    4. Glutathione S-transferase M1 null genotype as a risk modifier for solvent-induced chronic toxic encephalopathy
    Open this publication in new window or tab >>Glutathione S-transferase M1 null genotype as a risk modifier for solvent-induced chronic toxic encephalopathy
    Show others...
    1996 (English)In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 22, no 5, p. 360-363Article in journal (Refereed) Published
    Abstract [en]

    Objectives Exposure to organic solvents increases the risk of neuropsychiatric disability or chronic toxic encephalopathy (CTE). Polymorphisms in the biotransformation of xenobiotics and solvents may influence individual susceptibility to develop toxic effects. In this study the problem of whether there could be any association between the glutathione S-transferase M1 (GSTM1) null genotype and the risk for CTE, with regard to solvent exposure, was investigated.

    Methods Sixty patients referred to a clinic because of some degree of some degrees of psychiatric or neurological symptoms, as well as exposure to solvents, were examined by means of a validated questionnaire and psychometric testing. The degree of exposure to solvents was assessed by a thorough interview. According to clinical findings, the patients were classified into three categories as those with solvent-induced CTE, those with incipient CTE, and those who were non-CTE patients. Afterwards, leukocyte DNA (deoxyribonucleic acid) was isolated and the GSTM1 null genotype was determined by an assay based on polymerase chain reaction, blindly with regard to both exposure and disease status.

    Results The relative proportion (RP) of GSTM1 null genotypes was significantly increased for patients with a diagnosed CTE when they were compared with non-CTE patients (RP 2.55, 95% confidence interval 1.0--6.2). Dichotomizing the patients by high and low exposure revealed an increased risk for both GSTM1 gene carriers and the GSTM1 null genotype in the high-exposure group, the relative risks (RR) being 4.5 and 7.9, respectively. The chi-square for the Mantel extension for trend was 6.2 (P=0.025).

    Conclusion The GSTM1 null genotype acts as a risk modifier for CTE among patients occupationally exposed to solvents. The risk seems to increase in a dose-dependent fashion.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84801 (URN)10.5271/sjweh.154 (DOI)
    Available from: 2012-10-22 Created: 2012-10-22 Last updated: 2017-12-07Bibliographically approved
    5. Interaction between smoking and glutathione S-transferase polymorphisms in solvent-induced chronic toxic encephalopathy
    Open this publication in new window or tab >>Interaction between smoking and glutathione S-transferase polymorphisms in solvent-induced chronic toxic encephalopathy
    2002 (English)In: Toxicology and industrial health, ISSN 0748-2337, E-ISSN 1477-0393, Vol. 18, no 6, p. 289-296Article in journal (Refereed) Published
    Abstract [en]

    Exposure to organic solvents is still common in industrial and other work environments, and increases the risk of chronic toxic encephalopathy (CTE). Genetic variation in metabolic enzymes for solvents and other xenobiotics may modify the risk of developing toxic effects. Therefore, we investigated the presence of null genotypes for glutathione S-transferases M1 and T1 (GSTM1, GSTT1) and two genetic polymorphisms of microsomal epoxide hydrolase (mEPHX) in relation to the risk for chronic toxic encephalopathy (CTE) when exposed to solvents and smoking. We genotyped 115 patients who were classified into three categories: CTE (n = 56), incipient CTE (n = 27) and non-CTE (n = 32) patients. DNA was isolated from leucocytes and the GSTM 1 and GSTT1 null genotypes were determined by multiplex-polymerase chain reaction. The two polymorphisms of mEPHX were analysed by PCR-RFLP (restriction fragment length polymorphism) based assays. All analyses were performed blindly with regard to both exposure and disease status. An increased binomial regression risk ratio = 2.5, 95% confidence interval (CI) 1.5-4.2, of the GSTM1 null genotype for CTE was found in smokers and for the GSTT1 null genotype (binomial regression risk ratio 1.5, 95% CI 1.0-2.0). In nonsmokers, the GSTM1 null genotype did not confer any risk for CTE. None of the studied mEPHX polymorphisms were associated with an increased risk for CTE. We suggest that the GSTM1 null genotype in smokers is a possible risk for solvent-induced CTE.

    Keywords
    chronic toxic encephalopathy, molecular epidemiology, polymorphism, smoking, solvent exposure
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-46280 (URN)10.1191/0748233702th152oa (DOI)
    Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13Bibliographically approved
  • 1120.
    Ahmadi, Ahmad
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Bivik, Cecilia
    Linköping University, Department of Biomedicine and Surgery, Dermatology. Linköping University, Faculty of Health Sciences.
    Söderkvist, Peter
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Monoamine oxidase A and B genes polymorphisms in Parkinson's diseaseManuscript (preprint) (Other academic)
    Abstract [en]

    Parkinson's disease (PD) is a common progressive neurodegenerative disorder characterized by degeneration of nig:rostriatal dopaminergic neurons including the loss of cell bodies in the pars compacta of substantia nigra (SN). The mechanism for neurodegeneration is unknown, but the pathogenesis is considered to be multifactorial involving exposure for toxins, genetic inheritance, age, oxidative stress and mitochondrial electron transport chain defects. This study has been focused on polymorphisms in the genes for the enzymes monoamine oxidase A and B (MAO-A, MAO-B) and relation to smoking for the development of idiopathic Parkinson's disease. MAO enzymes are important in the dopamine metabolism and in the detoxification of neurotoxins. During metabolism of dopamine, MAO generates large amounts of free radicals and hydrogen peroxide, and may damage the neurons in substantia nigra, which has been suggested as a pathologic mechanism for PD.

    Blood samples were collected from 256 PD patients, age 30-80 years, and 582 unrelated control individuals, age 31 - 78 years, from southeastern Sweden.

    Two polymorphisms (exon 8 and exon 14) located in the MAO-A gene and one polymorphism located in the MA O-B gene were examined, with denatming HPLC, PCR-RFLP or DNA sequencing. Genotype and allele frequencies were determined for patients and controls. No statistical significant difference was revealed between any of the polymorphisms in the MAO-A and MAO-B genes and Parkinson's disease. Smoking displayed an enviromnental exposure with a strong decreased risk for both male (OR=0.40, 95% CI 0.25 - 0.63) and female (OR=0.48, 95% CI 0.25-0.89) PD without any interaction with MAO genotype.

    The polymorphisms in MAO genes might therefore not be acting as modifiers of risk for developing of PD either by itself or by interacting with smoking. With respect to the size of the study (256 PD patients and 582 controls) MAO polymorphisms do not represent any predisposing factor or a weak PD susceptibility factor.

  • 1121.
    Ahmadi, Ahmad
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Fredriksson, Mats
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Jerregård, H.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Åkerbäck, Anita
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Fall, Per-Arne
    Linköping University, Department of Neuroscience and Locomotion, Geriatrics. Linköping University, Faculty of Health Sciences.
    Rannug, A.
    National Institute for Working Life, Solna and Inst. of Environ. Medicine, Karolinska Institutet, Stockholm, Sweden.
    Axelson, Olav
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Söderkvist, Peter
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    GSTM1 and mEPHX polymorphisms in Parkinson's disease and age of onset2000In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 269, no 3, p. 676-680Article in journal (Refereed)
    Abstract [en]

    Both environmental and genetic factors are involved in the development of PD and biotransformation of exogenous and endogenous compounds and may play a role in inter-individual susceptibility. Therefore, we investigated the presence of null genotypes of GSTM1, GSTT1, and two polymorphisms of mEPHX in subjects with Parkinson's disease and in a reference population. The study included 35 male PD patients and a male control group including 283 subjects. Homozygosity of the histidine (H) 113 isoform of mEPHX was significantly increased in PD patients (odds ratio = 3.8 CI 95% 1.2–11.8) and analysis of allele frequencies displayed an increased frequency of the H-allele among PD patients (odds ratio = 1.9 CI 95% 1.1–3.3). However, a significantly elevated median age for the onset of PD was found among GSTM1 gene carriers (median age = 68 years) compared to PD patients being GSTM1 null genotypes (median age = 57 years). Our observations suggest that (H) 113 isoform of mEPHX, which has been suggested as a low activity isoform, is overrepresented in PD patients and that inherited carriers of the GSTM1 gene postpone the onset of PD. These detoxification pathways may represent important protective mechanisms against reactive intermediates modifying the susceptibility and onset of PD.

  • 1122.
    Ahmadi, Ahmad
    et al.
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Johansson, Sofia
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Söderkvist, Peter
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Manganese superoxide dismutase and NDUFV2 polymorphisms and susceptibility to Parkinson's diseaseManuscript (preprint) (Other academic)
    Abstract [en]

    Mitochondrial dysfunction has been hypothesized to contribute to the pathogenesis of Parkinson's disease (PD). Oxidative stress and production of oxygen radicals is produced in mitochondria. The superoxide dismutases (SOD) potentially play an important role in PD by detoxifying superoxide radicals. Oxidative stress has also an important role to decrease Complex I activity in the mitochondria. In addition, Complex I contains several subunits, where one, NDUFV2, plays a major role in the electron transport pathway of Complex I in substantia nigra.

    The aim of this project was to study polymorphisms in MTS-SOD2 and the Complex I subunit, NDUFV2 as predisposing factors for the development of idiopathic PD.

    Blood samples from 200 PD and 404 population controls were collected from the Southeastern part of Sweden. DNA was isolated and the polymorphisms were analyzed by pyrosequencing and direct dideoxy termination sequencing.

    Genotypes and allele frequencies were compared for the patient and control groups with Χ2 statistics. No statistical significant difference was evident for any of the polymorphisms neither in MTS-SOD2 (OR=0<85, 95% CI, 0<52-1.38) nor NDUFV2 (OR=0.64, 95% CI, 0.24-1.64) genes and PD.

    These results indicate that the MTS-SOD2 and NDUFV2 gene variants do not contribute to PD pathogenesis.

  • 1123.
    Ahmadi, Ahmad
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Jonsson, Pia
    Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Flodin, Ulf
    Linköping University, Department of Clinical and Experimental Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
    Söderkvist, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Interaction between smoking and glutathione S-transferase polymorphisms in solvent-induced chronic toxic encephalopathy2002In: Toxicology and industrial health, ISSN 0748-2337, E-ISSN 1477-0393, Vol. 18, no 6, p. 289-296Article in journal (Refereed)
    Abstract [en]

    Exposure to organic solvents is still common in industrial and other work environments, and increases the risk of chronic toxic encephalopathy (CTE). Genetic variation in metabolic enzymes for solvents and other xenobiotics may modify the risk of developing toxic effects. Therefore, we investigated the presence of null genotypes for glutathione S-transferases M1 and T1 (GSTM1, GSTT1) and two genetic polymorphisms of microsomal epoxide hydrolase (mEPHX) in relation to the risk for chronic toxic encephalopathy (CTE) when exposed to solvents and smoking. We genotyped 115 patients who were classified into three categories: CTE (n = 56), incipient CTE (n = 27) and non-CTE (n = 32) patients. DNA was isolated from leucocytes and the GSTM 1 and GSTT1 null genotypes were determined by multiplex-polymerase chain reaction. The two polymorphisms of mEPHX were analysed by PCR-RFLP (restriction fragment length polymorphism) based assays. All analyses were performed blindly with regard to both exposure and disease status. An increased binomial regression risk ratio = 2.5, 95% confidence interval (CI) 1.5-4.2, of the GSTM1 null genotype for CTE was found in smokers and for the GSTT1 null genotype (binomial regression risk ratio 1.5, 95% CI 1.0-2.0). In nonsmokers, the GSTM1 null genotype did not confer any risk for CTE. None of the studied mEPHX polymorphisms were associated with an increased risk for CTE. We suggest that the GSTM1 null genotype in smokers is a possible risk for solvent-induced CTE.

  • 1124.
    Ahmadi, Shervin Parvini
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Hansson, Anders
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Parallel Exploitation for Tree-Structured Coupled Quadratic Programming in Julia2018In: Proceedings of the 22nd International Conference on System Theory, Control and Computing, IEEE, 2018, p. 597-602Conference paper (Refereed)
    Abstract [en]

    The main idea in this paper is to implement a distributed primal-dual interior-point algorithm for loosely coupled Quadratic Programming problems. We implement this in Julia and show how can we exploit parallelism in order to increase the computational speed. We investigate the performance of the algorithm on a Model Predictive Control problem.

  • 1125.
    Ahmadkhaniha, D.
    et al.
    Jonkoping Univ, Sweden.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Leisner, P.
    Jonkoping Univ, Sweden; RISE Res Inst Sweden, Sweden.
    Zanella, C.
    Jonkoping Univ, Sweden.
    Effect of SiC particle size and heat-treatment on microhardness and corrosion resistance of NiP electrodeposited coatings2018In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 769, p. 1080-1087Article in journal (Refereed)
    Abstract [en]

    Electrodeposition of NiP composite coatings with nano and sub-micron sized SiC has been carried out to investigate the possibility of replacing hard chromium coatings. The composition and structure of the coatings were evaluated by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis, respectively. Microhardness was measured by Vickers indentation and polarization measurements were carried out to study the corrosion behavior of the coatings. The results showed that submicron particles can be codeposited with a higher content as compared to nano sized ones. However, even if a smaller amount of the nano-sized SiC particles are incorporated in the coating, the contribution to an increasing microhardness was comparable with the submicron sized particles, which can be related to the higher density of codeposited particles. SiC particles did not change the anodic polarization behavior of NiP coatings in a 3.5% NaCl solution. Finally, the effect of heat-treatment on the coatings properties at 400 degrees C for 1 h was studied to investigate the contribution of particles and heat-treatment on hardness and corrosion properties. It was found that the heat-treatment doubled the microhardness and changed the anodic polarization behavior of the coatings from passive to active with respect to the asplated conditions. (C) 2018 Elsevier B.V. All rights reserved.

  • 1126.
    Ahmed Aamir, Syed
    et al.
    University of Bielefeld, Germany .
    Angelov, Pavel
    AnaCatum Design AB, Linkoping, Sweden .
    Wikner, Jacob
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    1.2-V Analog Interface for a 300-MSps HD Video Digitizer in Core 65-nm CMOS2014In: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, E-ISSN 1557-9999, Vol. 22, no 4, p. 888-898Article in journal (Refereed)
    Abstract [en]

    This paper describes the front-end of a fully integrated analog interface for 300 MSps, high-definition video digitizers in a system on-chip environment. The analog interface is implemented in a 1.2 V, 65-nm digital CMOS process and the design minimizes the number of power domains using core transistors only. Each analog video receiver channel contains an integrated multiplexer with a current-mode dc-clamp, a programmable gain amplifier (PGA) and a pseudo second-order RC low-pass filter. The digital charge-pump clamp is integrated with low-voltage bootstrapped tee-switches inside the multiplexer, while restoring the dc component of ac-coupled inputs. The PGA contains a four-stage fully symmetric pseudo-differential amplifier with common-mode feedforward and inherent common-mode feedback, utilized in a closed loop capacitive feedback configuration. The amplifier features offset cancellation during the horizontal blanking. The video interface is evaluated using a unique test signal over a range of video formats for INL+/DNL+, INL-/DNL-. The 0.07-0.39 mV INL, 2-70 mu V DNL, and 66-74 dB of SFDR, enable us to target various formats for 9-12 bit Low-voltage digitizers.

  • 1127.
    Ahmed Aamir, Syed
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Harikumar, Prakash
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Wikner, Jacob J
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Frequency compensation of high-speed, low-voltage CMOS multistage amplifiers2013In: IEEE International Symposium on Circuits and Systems (ISCAS), 2013, IEEE conference proceedings, 2013, p. 381-384Conference paper (Refereed)
    Abstract [en]

    This paper presents the frequency compensation of high-speed, low-voltage multistage amplifiers. Two frequency compensation techniques, the Nested Miller Compensation with Nulling Resistors (NMCNR) and Reversed Nested Indirect Compensation (RNIC), are discussed and employed on two multistage amplifier architectures. A four-stage pseudo-differential amplifier with CMFF and CMFB is designed in a 1.2 V, 65-nm CMOS process. With NMCNR, it achieves a phase margin (PM) of 59° with a DC gain of 75 dB and unity-gain frequency (fug) of 712 MHz. With RNIC, the same four-stage amplifier achieves a phase margin of 84°, DC gain of 76 dB and fug of 2 GHz. Further, a three-stage single-ended amplifier is designed in a 1.1-V, 40-nm CMOS process. The three-stage OTA with RNIC achieves PM of 81°, DC gain of 80 dB and fug of 770 MHz. The same OTA achieves PM of 59° with NMCNR, while maintaining a DC gain of 75 dB and fug of 262 MHz. Pole-splitting, to achieve increased stability, is illustrated for both compensation schemes. Simulations illustrate that the RNIC scheme achieves much higher PM and fug for lower values of compensation capacitance compared to NMCNR, despite the growing number of low voltage amplifier stages.

  • 1128.
    Ahmed, Ali
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    A Systematic Literature Review of "Usability Inspection Methods"2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Objective: Usability inspection methods are a class of usability evaluation methods, applied by usability evaluators to assess usability related aspects of different user interfaces. Different usability inspection methods are proposed so far to evaluate user interfaces in a better way. This systematic literature review summarized different usability evaluation methods, with more focus on two widely used inspection methods. The review also summarized the problems with these two methods and probable proposed solution to cope with these problems.

    Method: A systematic review method as described by Kitchenham [3] was followed to carry out this review. The identified problems in the review were structured in a form of questions. The search to find the relevant data that address the identified questions were conducted on the basis of planned search strategies. Papers were selected on the basis of inclusion and exclusion criteria in accordance with the quality checklist; followed by data extraction and synthesis strictly characterized by quality checklist, inclusion and exclusion criteria to attain better results.

    Results and discussion: Despite of its advantages there still exists many weaknesses in Heuristic evaluation (HE) and Cognitive walk-through (CW) methods. Different studies have highlighted different factors that may influence the results. Those factors include number of evaluators, evaluator’s perception and experience, time, environment, cost, indigenous design, the way method applied and acquired software.

    Conclusion: To get better evaluation results, it is best to use different techniques for usability evaluation of single software or optimize existing techniques.

  • 1129.
    Ahmed, Ali
    School of Management and Economics Växjö University, Sweden.
    Are religious people more prosocial? A quasi-experimental study with madrasah pupils in a rural community in India2009In: Journal for the Scientific Study of Religion, ISSN 0021-8294, E-ISSN 1468-5906, Vol. 48, no 2, p. 368-374Article in journal (Refereed)
    Abstract [en]

    Using quasi-experimental data, this paper examines the relationship between religiosity and prosocial behavior. In contrast to previous studies which identify religious people by how often they attend religious services or by their self-reported religiosity, this study compares the behavior of highly devout students who are preparing to enter the clergy, to the behavior of other students in a public-goods game and in the dictator game. The results show that religious students were significantly more cooperative in the public-goods game and significantly more generous in the dictator game than other students.

  • 1130.
    Ahmed, Ali
    Växjö University.
    Breeding Bin Ladens: America, Islam and the future of Europe (Zachary Shore, 2006)2008In: Ethnic and Racial Studies, ISSN 0141-9870, E-ISSN 1466-4356, Vol. 31, no 3, p. 640-641Article, book review (Refereed)
  • 1131.
    Ahmed, Ali
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Co-ethnic preferences in a cooking game: a study based on Come Dine With Me in Sweden2013In: Ethnic and Racial Studies, ISSN 0141-9870, E-ISSN 1466-4356, Vol. 36, no 12, p. 2220-2236Article in journal (Refereed)
    Abstract [en]

    This study examines ethnic preferences using data from the television cooking show Come Dine With Me in Sweden. Amateur chefs compete by hosting dinner parties. Contestants rate each others performance and the host with the highest ratings wins a cash prize. The show gives an unorthodox opportunity to study ethnic preferences in a high-stakes game environment. The analysis of the collected data shows that native Swedish contestants rate co-ethnic hosts significantly more favourably than they rate other hosts, demonstrating the existence of co-ethnic preferences. This observation seems to be an outcome of own-group favouritism rather than dislike against other groups. Also, the observed co-ethnic preference is assumed to be subtle or non-conscious based on the nature of the analysed data.

  • 1132.
    Ahmed, Ali
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Commentary: Some thoughts on field experiments on housing discrimination from a European view2015In: Cityscape: A Journal of Policy Development and Research, ISSN 1936-007X, Vol. 17, no 3, p. 149-154Article in journal (Refereed)
  • 1133.
    Ahmed, Ali
    Linnaeus University, Växjö, Sweden and Swedish Collegium for Advanced Study, Uppsala, Sweden.
    Conditional reciprocity in the investment game2011In: The Social science journal (Fort Collins), ISSN 0362-3319, E-ISSN 1873-5355, Vol. 48, no 2, p. 404-408Article in journal (Refereed)
    Abstract [en]

    This paper investigates whether people are conditional reciprocators in an investment game experiment, in the sense that the more they are trusted, the more they reciprocate. The results show that the majority of participants are conditional reciprocators but that they can be classified into three types: (1) exploitative reciprocators who do not reciprocate and exploit trust; (2) egoistic reciprocators who neither exploit nor reward trust; and (3) generous reciprocators who reward trusting behavior.

  • 1134.
    Ahmed, Ali
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Etnisk diskriminering - vad vet vi, vad behöver vi veta och vad kan vi göra?2015In: Ekonomisk Debatt, ISSN 0345-2646, Vol. 43, no 4, p. 18-28Article in journal (Refereed)
    Abstract [sv]

    Diskriminering är ett avsevärt hinder på arbetsmarknaden, bostadsmarknaden och andra marknader för personer med utländsk bakgrund. I Sverige finns lagstiftning som förbjuder diskriminering och en myndighet som har tillsyn över problematiken. Men vad säger forskningen om etnisk diskriminering i Sverige? Denna översikt redogör för nationalekonomiska undersökningar som entydigt har funnit belägg för etnisk diskriminering. I ljuset av denna översikt förs en diskussion kring det vi känner till och det vi behöver känna till. Slutligen framförs förslag om hur arbetet mot etnisk diskriminering kan förbättras.

  • 1135.
    Ahmed, Ali
    School of Business and Economics Linnaeus University Växjö, Sweden.
    Muslim discrimination: evidence from two lost letter experiments2010In: Journal of Applied Social Psychology, ISSN 0021-9029, E-ISSN 1559-1816, Vol. 40, no 4, p. 888-898Article in journal (Refereed)
    Abstract [en]

    Since the 9/11 terrorist attacks, there has been considerable concern about whether Muslims living in Western countries are targets of prejudice. A considerable amount of survey-based evidence suggests that Muslims are victims of discrimination. This paper tested this hypothesis. Two lost-letter experiments were conducted to test whether the difference in returned letters would be attributable to whether the addressee was Muslim or Swedish. The results show that Muslims receive far fewer letters than do Swedes. However, this discrimination only appears when the lost letters contain money; in which case, the finder gains by not posting the letter.

  • 1136.
    Ahmed, Ali
    Växjö universitet.
    Vad säger ett efternamn?: en experimentell studie av etnisk diskriminering2004Report (Other academic)
  • 1137.
    Ahmed, Ali
    Växjö University, Sweden.
    What is in a surname? The role of ethnicity in economic decision making2010In: Applied Economics, ISSN 0003-6846, E-ISSN 1466-4283, Vol. 42, no 21, p. 2715-2723Article in journal (Refereed)
    Abstract [en]

    This article reports results from two experiments that investigate possible incidence of discrimination against people with foreign backgrounds in Sweden. In the first experiment, participants played the trust game and the dictator game with co-players of different ethnic affiliation. The family name of the players was exposed to their co-players. Results for the trust game showed no significant discrimination against co-players with foreign backgrounds. On the other hand, the results for the dictator game showed a statistically significant discriminatory behaviour by men against co-players with non-European backgrounds. The discriminatory behaviour was solely a male phenomenon. In the second experiment, the dictator game was replicated to check the stability of the results in the first experiment. The second experiment also examined whether people with foreign backgrounds discriminate against other people with foreign backgrounds; that is, the purpose was to discover whether discrimination is systematic. The observations in the second experiment underlined the results found in the first experiment: foreign co-players are discriminated against by Swedish players. However, we did not find that people with foreign backgrounds discriminated against other people with foreign backgrounds.

  • 1138.
    Ahmed, Ali
    Swedish Collegium for Advanced Study, Uppsala University, Sweden and Linnaeus University, Växjö, Sweden.
    Women are not always less competitive than men: evidence from Come Dine with Me2011In: Applied Economics Letters, ISSN 1350-4851, E-ISSN 1466-4291, Vol. 18, no 12, p. 1099-1101Article in journal (Refereed)
    Abstract [en]

    Are women less competitive than men? Many experimental and nonexperimental studies have documented gender differences in competitiveness. This article presents the results from a study that examines gender differences in competitiveness in the television show Come Dine with Me. It is a cooking show in which amateur chefs compete against each other for a cash prize. The show provides an unusual opportunity to study gender differences in a high-stakes game environment. The results demonstrate that there are no gender differences in competitiveness.

  • 1139.
    Ahmed, Ali
    et al.
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences. Swedish Collegium for Advanced Study, Uppsala, Sweden.
    Aldén, Lina
    Linnéuniversitetet, Växjö, Sweden.
    Hammarstedt, Mats
    Linnéuniversitet, Växjö, Sweden.
    Perceptions of gay, lesbian, and heterosexual domestic violence among undergraduates in Sweden2013In: International Journal of Conflict and Violence, ISSN 1864-1385, E-ISSN 1864-1385, Vol. 7, no 2, p. 249-260Article in journal (Refereed)
    Abstract [en]

    An experimental study of perceptions about gay, lesbian, and heterosexual domestic violence in Sweden. Undergraduate students (N = 1009) read one of eight fictitious scenarios of domestic violence in married couple relationships, where sexual orientation, sex of victim and batterer, and severity of violence were varied. Perceptions of seriousness of the described incident and attitudes toward women, gays and lesbians were measured. Domestic violence was perceived as more serious in cases where: the respondent was a woman, the batterer was a man, the victim was a woman, or the battering was severe. Wife-battering in a heterosexual relationship was considered the most serious case in both the less and more severe battering scenario. Where battering was less severe, domestic violence in gay and lesbian relationships was perceived as more serious than heterosexual husband-battering; this difference disappeared in the severe battering scenario. Negative attitudes toward gays, lesbians, and women were associated with less concern about domestic violence in all types of relationships. The findings suggest that stereotypes about gays, lesbians, and women affect perceptions of domestic violence, but mainly when violence is less severe.

  • 1140.
    Ahmed, Ali
    et al.
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Andersson, Lina
    Linnaeus University, Växjö, Sweden.
    Hammarstedt, Mats
    Linnaeus University, Växjö, Sweden.
    Are gay men and lesbians discriminated against in the hiring process?2013In: Southern Economic Journal, ISSN 0038-4038, E-ISSN 2325-8012, Vol. 79, no 3, p. 565-585Article in journal (Refereed)
    Abstract [en]

    This article presents the first field experiment on sexual orientation discrimination in the hiring process in the Swedish labor market. Job applications were sent to about 4000 employers in 10 different occupations in Sweden. Gender and sexual orientation were randomly assigned to applications. The results show that sexual orientation discrimination exists in the Swedish labor market. The discrimination against the gay male applicant and the lesbian applicant varied across different occupations and appears to be concentrated in the private sector. The results also show that the gay male applicant was discriminated against in typical male-dominated occupations, whereas the lesbian applicant was discriminated against in typical female-dominated occupations. Theoretical implications are discussed.

  • 1141.
    Ahmed, Ali
    et al.
    Växjö University, Sweden.
    Andersson, Lina
    Växjö University, Sweden.
    Hammarstedt, Mats
    Växjö University, Sweden.
    Can discrimination in the housing market be reduced by increasing the information about the applicants?2010In: Land Economics, ISSN 0023-7639, E-ISSN 1543-8325, Vol. 86, no 1, p. 79-90Article in journal (Refereed)
    Abstract [en]

    We investigate how increasing the information about applicants affects discrimination in the rental housing market. We let four fictitious applicants, two with typical Arab/Muslim names and two with typical Swedish names, use application letters containing different amounts of information to apply for apartments over the Internet in Sweden. The Arab/Muslim applicants received fewer responses from the landlords than did the Swedish applicants. All of the applicants gained by providing more information about themselves, but the amount of discrimination against the Arab/Muslim applicants remained unchanged, indicating that increasing the amount of information about the applicants will not reduce discrimination.

  • 1142.
    Ahmed, Ali
    et al.
    Linnéuniversitet och Swedish Collegium for Advanced Study.
    Andersson, Lina
    Linnéuniversitet .
    Hammarstedt, Mats
    Linnéuniversitet .
    Diskriminering mot icke-heterosexuella i anställningssituationen2011Report (Other academic)
    Abstract [en]

    This paper presents the first field experiment on sexual orientation discrimination in the hiring process in the Swedish labor market. Job applications were sent to about 4,000 employers in 10 different occupations in Sweden. Gender and sexual orientation were randomly assigned to applications. The results show that sexual orientation discrimination exists in the Swedish labor market. The discrimination against gays and lesbian varies across different occupations and appears only in the private sector. The results also seem to suggest a new dimension of traditional gender roles; the gay applicant was discriminated against in typical male-dominated occupations whereas the lesbian applicant was discriminated against in typical female-dominated occupations. Thus, the results suggest that gays to some extent face the same obstacles on the labor market as heterosexual women.

  • 1143.
    Ahmed, Ali
    et al.
    Linnaeus University, Växjö, Sweden and Swedish Collegium for Advanced Study, Uppsala, Sweden.
    Andersson, Lina
    Linnaeus University, Växjö, Sweden.
    Hammarstedt, Mats
    Linnaeus University, Växjö, Sweden.
    Does age matter for employability? A field experiment on ageism in the Swedish labor market2012In: Applied Economics Letters, ISSN 1350-4851, E-ISSN 1466-4291, Vol. 19, no 4, p. 403-406Article in journal (Refereed)
    Abstract [en]

    This article presents the findings of the first field experiment on age discrimination in the Swedish labour market. Pairs of matched applications, one from a fictitious 31-year-old male applicant and one from a fictitious 46-year-old male applicant, were sent to employers with job openings for restaurant workers and sales assistants. Employers' responses to the applicants were then recorded. The experimental data provide clear and strong evidence of significant ageism in the Swedish labour market. On average, the younger applicant received over 3 times more responses from employers looking to hire a restaurant worker and over 4 times more responses from employers looking to hire a sales assistant than the older applicant. Therefore, the older applicant received significantly fewer invitations for interviews and job offers than the younger applicant in both occupations examined.

  • 1144.
    Ahmed, Ali
    et al.
    Växjö University, Sweden.
    Andersson, Lina
    Växjö University, Sweden.
    Hammarstedt, Mats
    Växjö University, Sweden.
    Ethnic discrimination in the market place of small business transfers2009In: Economics Bulletin, ISSN 1545-2921, E-ISSN 1545-2921, Vol. 29, no 4, p. 3050-3058Article in journal (Refereed)
    Abstract [en]

    This paper presents the first field experiment regarding ethnic discrimination in the market place of small business transfers. We let two fictitious prospective buyers, one with a typical Swedish name and one with a typical Arab/Muslim name, respond to advertisements of small business transfers on the Internet in Sweden. We then recorded the number contacts achieved by each fictitious buyer with sellers. We found that sellers discriminated against the buyer with an Arab/Muslim name in the sense that the buyer with an Arab/Muslim name obtained fewer contacts with sellers than did the buyer with a Swedish name.

  • 1145.
    Ahmed, Ali
    et al.
    Linnaeus University, Växjö, Sweden and the Swedish Collegium for Advanced Study, Uppsala, Sweden.
    Andersson, Lina
    Linnaeus University, Växjö, Sweden.
    Hammarstedt, Mats
    Linnaeus University, Växjö, Sweden.
    Inter- and Intra-Household Earnings Differentials among Homosexual and Heterosexual Couples2011In: British Journal of Industrial Relations, ISSN 0007-1080, E-ISSN 1467-8543, Vol. 49, no S2, p. S258-S278Article in journal (Refereed)
    Abstract [en]

    We present earnings differentials between homosexuals and heterosexuals. In line with previous research, we find that gay males earn less than heterosexual males, and that lesbians earn more than heterosexual females. However, when combining the individuals into households, our results are strikingly different: very small earnings differentials between gay households and heterosexual households are found. Lesbian households earn considerably less. The largest earnings inequalities between spouses are found among gay males followed by heterosexuals. Studying sexual orientation and earnings is complex, and household earnings have to be taken into consideration when conclusions are drawn.

  • 1146.
    Ahmed, Ali
    et al.
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Andersson, Lina
    Linnaeus University, Sweden.
    Hammarstedt, Mats
    Linnaeus University, Sweden.
    Sexual orientation and full-time monthly earnings, by public and private sector: evidence from Swedish register data2013In: Review of Economics of the Household, ISSN 1569-5239, E-ISSN 1573-7152, Vol. 11, no 1, p. 83-108Article in journal (Refereed)
    Abstract [en]

    In this paper we explore annual earnings as well as full-time monthly earnings differentials resulting from sexual orientation. We observe that gay males are at an earnings disadvantage compared to male heterosexuals regardless of which earnings measure we use. This earnings disadvantage is found to be larger when we compare gay and heterosexual males who are working full-time. In addition, the disadvantage is larger in the private than in the public sector. Lesbians, however, earn more than heterosexual females. This earnings advantage is considerably smaller when we study full-time monthly rather than annual earnings but an earnings advantage for lesbians at the top of the earnings distribution is documented regardless of which earnings measure we use. In addition, lesbians are doing better than female heterosexuals in the public sector. To sum up, the results indicate that gay males face obstacles on the labor market that hinder them from reaching top-level positions and high earnings. The earnings advantage observed for lesbians is likely to stem from the fact that lesbians devote more time to market work than heterosexual females do.

  • 1147.
    Ahmed, Ali
    et al.
    Linnaeus University, Växjö and Swedish Collegium for Advanced Study, Uppsala.
    Andersson, Lina
    Linnaeus University, Växjö.
    Hammarstedt, Mats
    Linnaeus University, Växjö.
    Sexual orientation and occupational rank2011In: Economics Bulletin, ISSN 1545-2921, E-ISSN 1545-2921, Vol. 31, no 3, p. 2422-2433Article in journal (Refereed)
    Abstract [en]

    This paper presents a study of differences in occupational rank between gay and heterosexual males as well as between lesbian and heterosexual females. We estimate different specifications of an ordered probit model on register data from Sweden. Our data consist of married heterosexual men and women and homosexual men and women living in civil unions. We find that homosexual men have a lower probability of working in a profession demanding a longer university education or a management profession than heterosexual men. In contrast, we find that homosexual women are more likely than heterosexual women to work in such professions.

  • 1148.
    Ahmed, Ali
    et al.
    Linnaeus University, Växjö, Sweden.
    Anxo, Dominique
    Linnaeus University, Växjö, Sweden.
    The Swedish Elderly Care2006Report (Other academic)
  • 1149.
    Ahmed, Ali
    et al.
    Växjö universitet.
    Ekberg, Jan
    Växjö universitet.
    Fältexperiment för att studera etnisk diskriminering på arbets- och bostadsmarknaden: bidrag, kritik och framtid2008In: Efterfrågad arbetskraft?: årsbok 2008 från forskningsprofilen Arbetsmarknad, migration och etniska relationer (AMER) vid Växjö universitet / [ed] S. Lundberg och E. Platzer, Växjö University Press , 2008, p. 101-117Chapter in book (Other academic)
  • 1150.
    Ahmed, Ali
    et al.
    Växjö universitet.
    Ekberg, Jan
    Växjö universitet.
    Fältexperiment för att studera etnisk diskriminering på den svenska arbets- och bostadsmarknaden2009In: Socialvetenskaplig tidskrift, ISSN 1104-1420, Vol. 16, no 2, p. 105-122Article in journal (Refereed)
    Abstract [sv]

    Under senare år har fältexperiment använts för att studera etnisk diskriminering på den svenska arbets- och bostadsmarknaden. I nedanstående framställning ges en presentation av fältexperiment som metod och en översikt över den forskning som genomförts med hjälp av fältexperiment i Sverige. Dessutom görs en framåtblickande diskussion.

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